Diagnostic Aids
WARNING: This page is about a different car, the 2017 GMC Acadia. However, it is still accessible from the selected car via links, so may be relevant.
If the scan tool ISS/OSS supply voltage parameter is out of range, the fault could also be caused by the transmission output shaft speed sensor.
Damage or misalignment of the 4-5-6 clutch and 3-5-R clutch housing reluctor machined teeth surface may cause a speed sensor malfunction.